Acoustically deadened piling



Sept. 24 1 968 K. 5. A 3,402,560

ACOUST I CALLY DEADENED FILING Filed July 6, 1966 2 She ets-Sheet 1 l l H f H 4" l w //o' /5. I I HIS i ,6 Fig.2 Fig.3

INVENTOR.

KOO. Stand mm Balm h United States Patent 3,402,560 ACOUSTICALLY DEADENED PILING Karl Statfan Alm, Nacka, Sweden, assignor to Atlas Copco Aktiebolag, Nacka, Sweden, a corporation of Sweden Filed July 6, 1966, Ser. No. 563,222

Claims priority, application Sweden, July 13, 1965,

9,207/ 65 7 Claims. (Cl. 61-53) ABSTRACT OF THE DISCLOSURE Acoustically deadened piling is provided and including a substantially elongated solid steel pile body capable of withstanding longitudinally directed impacts and having disposed substantially over the surface of one and/or both sides thereof a coating of visco-elastic material, a thin metallic shell disposed over said coating in sandwich fashion and covering said coating, and welded points between said shell and said pile body for holding the entire structure together while still providing a spaced apart relationship between said body and said shell for accommodating said coating. Also included within the concept of said welded points is a welded seam extending along one end edge of said piling body and said shell which provides a firm driving edge for said piling body as it is driven into the ground.

This invention relates to piling and more particularly to acoustically deadened piling. During driving of metallic piles and particularly of sheet piling by the aid of percussive machines such as pneumatic hammers one receives with bare steel piles a ringing metallic noise with very high sound pressure levels and within the frequency range of 2000 to 8000 hertz. This high frequency noise is heavily disturbing for the surroundings and makes pile driving in habitatcd areas difiicult to tolerate. It is the primary object of the invention to provide an acoustically deadened piling which during driving generates substantially reduced sound pressure levels at the high frequencies in question. The reduction reached is in the order of magnitude of 10 decibels corresponding to a subjective reduction in noise perception to about half.

For the above and other purposes there is according to the invention provided an acoustically deadened piling comprising an elongated steel pile body, a band shaped coating of vibration damping material on the surface of said pile body extending along the major portion of its length, a metallic shell substantially parallel with the outer surface of said pile body and covering said coating, and means connecting said shell to said pile body under the formation of a clearance therebetween filled by said coating.

The shell keeps the band of vibration damping material in place on the surface of the pile, protects the band from wearing away during driving and maintains its thickness constant at the desired optimum value. The shell furthermore takes up and diverts outwardly the heat accumulating in the coating as a result of its vibration damping action. This effective heat diversion makes possible the use of temperature sensitive high molecular viscoelastic materials in the coating band and these material compositions are especially effective in deadening high frequency noise.

The above and other objects of the invention will become obvious from the following description and from the accompanying drawings in which two embodiments of the invention are illustrated by way of example. It should be understood that these embodiments are only illustrative of the invention and that various other modifications may be made within the scope of the claims.

3,402,560 Patented Sept. 24, 1968 In the drawings FIG. 1 is a cross sectional view through a steel pile embodying the invention. FIG. 2 is a longitudinal section on the line 2-2 in FIG. 1. FIG. 3 shows a perspective view of the lower end of the steel pile in FIG. 1. FIG. 4 is a cross section through modified sheet piling of Z-form embodying the invention. FIG. 5 is a longitudinal section on the line 5-5 in FIG. 4. FIG. 6 is a perspective view of the longer end of the piling in FIG. 4.

The piling or steel pile in FIGS. 1-3 is designated by 10 and is provided with locking flanges 11. The piling shown is commonly known to be of so called Larssentype. On one broad side of the pile 10 is applied a band extending along the major portion of the length of the pile and consisting of a coating 12 of vibration damping material. The coating 12 is covered by a sheet metal or steel shell 13 substantially parallel with the surface of the piling. The thickness of the shell is chosen equal to or close to a third of the thickness of the pile. The shell 13 is aflixed to the pile 10 by welding in the portions or spots 14 along the longitudinal edges of the shell 13. A welded seam 15 forms the lower edge of the shell 13. The welded portions 14 keep the shell 13 affixed to the piling under the formation of a clearance therebetween entirely filled by the coating 12. The coating band 12 is smaller in thickness than the shell 13. At its penetrating end the pile 10 has a reinforcing strip 16 welded thereto. The thickness of the strip 16 is greater than the sum of the thicknesses of the shell 13 and the coating band 12. During driving the reinforcement 16 penetrates into the ground in front of the shell 13 reducing the stresses acting thereagainst.

A coating material applicable in connection with the invention is rubber. The rubber is applied to the pile preferably in the form of a cold curing (cold vulcanizing) paste. One receives good noise deadening for example by the use of the synthetic polysulphide rubber sold under the trademark Thioflex" by Bigner & Co. Aktiebolag, Lidingo, Sweden. As an alternative there can be used a viscoelastic coating of high polymer mixture components with an optimal absorption of deformation energy within a temperature range between 20 and degrees Centigrade. Such viscoelastic compositions with the desired active temperature range are sold by Farbwerke Hoechst Aktiengesellschaft, Frankfurt am Main, The Federal German Republic, and may for example contain polymers of vinyl acetate, acrylic ester, vinyl propionate, vinyl acetate and vinyl chloride alone or in mixture or in some cases with an addition of a suitable softener. The usually narrow marked viscoelastic temperature range can be influenced as to its position and width by suitably varying the mixture components. In the polymer or copolymer mixture may be added mica or graphite or preferably the mica-mineral vermiculite to the extent of 20 to Especially vermiculite expanded through heating is advantageous because of its porosity.

As an example of the composition of the coating may be mentioned:

Percent Polyvinyl acetate Dibutyl phthalate (softener) 20 These components form a composite paste with vermiculite in the proportions 40/60%.

Polyvinyl propionate with the addition of 40 to 60% graphite or vermiculite.

In the embodiment according to FIG. 4 two Z-shaped steel piles 18, 19 are lockable to one another and to other similar piles by joining strips 20. In accordance with the preceding embodiment both piles 18, 19 are covered on the one broad side thereof by a sheet metal or steel shell 21 welded thereonto and covering the vibration damping coating band 22. For fixing of the central portions of the sheet metal shell 21 to the piles 18, 19 the shell 21 is provided with through holes 23 the edges of which are welded in the spots 24 fast to the piles 18, 19. Onto the penetrating end of the piles 18, 19 one welds reinforcement strips 26 with a thickness exceeding the thickness of the band 22 and the shell 21.

For purposes of increasing the sound deadening action the shell and the coating band may be applied in doublesided relation to the piles which in FIG. 4 is illustrated by line 25 at the opposite side of the shell 21 and band 22 on pile 19.

What I claim is:

1. An acoustically deadened piling comprising an elongated substantially solid steel pile body, a band shaped coating of vibration damping material on the surface of said pile body extending along the major portion of its length, a metallic shell substantially parallel with the outer surface of said pile body and covering said coating, and means connecting said shell to said pile body under the formation of a clearance therebetween filled by said coating.

2. An acoustically deadened piling comprising an elongated substantially solid sheet steel pile body, a band shaped coating of vibration clamping material covering the major portion of the surface of one side of said body and extending over the major portion thereof, a steel shell substantially parallel with the surface of said one broad side and covering said coating, said coating having a thickness smaller than said shell, and means connecting said shell to said body under the formation of a clearance therebetween substantially entirelyfilled by said coating.

3. Piling according to claim 2 in which the ratio between the thickness of said shell and the thickness of said body is equal or close to the value 1:3.

4. An acoustically deadened piling comprising an elongated substantially solid sheet steel pile body, a band shaped coating of vibration damping material covering the major portion of the surface of at least one side of said body and extending over the major portion thereof,- a steel shell substantially parallel with, the surface of said one side and covering said coating, Welded joints applied between said body and the longitudinal edges of said shell connecting said body and shell under the formation of a clearance therebetween filled by said coating, and a welded seam forming the lower edge of said shell.

5. Piling according to claim 4 in which said shell is provided with apertures therethrough, and additional Welded joints between the shell edge portions around said apertures and said body.

6. An acoustically deadened piling comprising an elongated substantially solid sheet steel pile body, a pair of band shaped coatings of vibration damping material each covering the major portion of one of the surfaces of the opposed sides of said body and extending over the major portion thereof, a pair of steel shells substantially parallel with the respective surfaces of said sides and covering said coatings thereon, said coatings having a thickness smaller than said shells, and means connecting said shells to said body under the formation of a clearance therebetween substantially entirely filled 'by said coatings.

7. An acoustically deadened piling comprising an elongated steel pile body, a band shaped coating of vibration damping material on the surface of said pile body extending along the major portion of its length, a metallic shell substantially parallel with the outer surface of said pile body and covering said coating, means connecting said shell to said pile body under the formation of a clearance therebetween filled by said coating, and a reinforcing strip disposed on one end edge of said pile body and connected thereto in front of said coating and said shell, the thickness of said strip being equal to or greater than the sum of the thickness of said shell and said coating.

References Cited UNITED STATES PATENTS JACOB SHAPIRO, Primary Examiner. 

